Descriptive epidemiology of Chronic Fatigue Syndrome (CFS) based on a nationwide survey in Japan

In order to clarify the epidemiological features of chronic fatigue
syndrome (CFS), a nationwide survey was conducted using the
Japanese version of the CDC Criteria prepared by the CFS
Research Group of Japan. All clinical departments of internal
medicine, pediatrics, psychiatry and neurology at university
hospitals and at ordinary hospitals with 200 or more beds were
surveyed. Major results were as follows: (1) Period
prevalence adjusted for response rate was 0.85 (0.63 for
males and 1.02 for females) per 100,000 population during the
year 1992; (2) Based on the first and final dates of hospital
visits, the prevalences on January 1 of 1992 and 1993 were
0.40 and 0.60 per 100,000 population, respectively,
suggesting an increasing trend; (3) Reported new cases during
1992 were 301, and the response adjusted-incidence was
estimated to be 0.46 per 100,000 person-years; (4) The
proportion of post-infectious CFS cases was 14.8% for both
sexes, and tended to be slightly higher among females than
males, but was not related to age. Three clusterings of two
cases were reported.